package com.hmdp.service.impl;

import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Autowired
    private StringRedisTemplate stringRedisTemplate;
    @Autowired
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) throws InterruptedException {
        // 缓存穿透
        Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById);

        // 互斥锁解决缓存击穿
        // Shop shop = queryWithMutex(id);

        // 逻辑过期解决缓存击穿
        // Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        return Result.ok(shop);
    }

    /**
     * 线程池
     */
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

//    /**
//     * 逻辑过期解决缓存击穿
//     * @param id 商铺id
//     * @return
//     */
//    public Shop queryWithLogicalExpire(Long id) {
//        String key = CACHE_SHOP_KEY + id;
//        // 从Redis中拿到商铺
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//        if (StrUtil.isBlank(shopJson)) {
//            return null;
//        }
//
//        // 命中，判断缓存是否过期
//        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
//        JSONObject data = (JSONObject) redisData.getData();
//        Shop shop = JSONUtil.toBean(data, Shop.class);
//        LocalDateTime expireTime = redisData.getExpireTime();
//        // 未过期，返回商铺信息
//        if (expireTime.isAfter(LocalDateTime.now())) {
//            // 未过期，返回商铺信息
//            return shop;
//        }
//        // 已过期，需要缓存建立
//        // 获取互斥锁
//        String lockKey = LOCK_SHOP_KEY + id;
//        Boolean flag = tryLock(lockKey);
//        if (flag) {
//            // 获取成功, 开启独立线程，缓存重建
//            CACHE_REBUILD_EXECUTOR.submit(() -> {
//                // 重建缓存
//                try{
//                    saveShop2Redis(id, 20L);
//                }catch (Exception e) {
//                    throw new RuntimeException(e);
//                }finally {
//                    unLock(lockKey);
//                }
//            });
//        }
//        // 获取锁失败，返回商铺信息
//        return shop;
//    }

//    /**
//     * 互斥锁解决缓存击穿
//     *
//     * @param id 商铺id
//     * @return 商铺信息
//     * @throws InterruptedException
//     */
//    public Shop queryWithMutex(Long id) throws InterruptedException {
//        String key = CACHE_SHOP_KEY + id;
//        // 从Redis中拿到商铺
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//        if (StrUtil.isNotBlank(shopJson)) {
//            return JSONUtil.toBean(shopJson, Shop.class);
//        }
//
//        if (shopJson != null) {
//            return null;
//        }
//
//        // 未命中，获取互斥锁
//        String lockKey = LOCK_SHOP_KEY + id;
//        if (!tryLock(lockKey)) {
//            // 获取锁失败，休眠并重试
//            Thread.sleep(50);
//            return queryWithMutex(id);
//        }
//        // 获取锁成功，实现逻辑
//        Shop shop = getById(id);
//        // 模拟重建的延时
//        Thread.sleep(200);
//        if (shop == null) {
//            // 将空值写入Redis
//            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
//            return null;
//        }
//        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
//        // 释放互斥锁
//        unLock(lockKey);
//        return shop;
//    }

//    /**
//     * 缓存穿透
//     *
//     * @param id 商铺id
//     * @return 商铺信息
//     */
//    public Shop queryWithPassThrough(Long id) {
//        String key = CACHE_SHOP_KEY + id;
//        // 从Redis中拿到商铺
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//        if (StrUtil.isNotBlank(shopJson)) {
//            return JSONUtil.toBean(shopJson, Shop.class);
//        }
//
//        if (shopJson != null) {
//            return null;
//        }
//
//        Shop shop = getById(id);
//        if (shop == null) {
//            // 将空值写入Redis
//            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
//            return null;
//        }
//        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
//        return shop;
//    }


//    private Boolean tryLock(String key) {
//        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10L, TimeUnit.SECONDS);
//        return BooleanUtil.isTrue(flag);
//    }
//
//    private void unLock(String key) {
//        stringRedisTemplate.delete(key);
//    }

    public void saveShop2Redis(Long id, Long expireSeconds) throws InterruptedException {
        Shop shop = getById(id);
        Thread.sleep(200);
        // 封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        // 写入Redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY, JSONUtil.toJsonStr(redisData));
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        // 删除Redis缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());
        // 更新数据库
        updateById(shop);

        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 判断是否需要根据坐标查询
        if(x == null || y == null){
            // 根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        // 计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        // 查询 Redis，按照距离排序、分页。
        GeoResults<RedisGeoCommands.GeoLocation<String>> search = stringRedisTemplate.opsForGeo().
                search(RedisConstants.SHOP_GEO_KEY + typeId,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end));

        if(search == null){
            return Result.ok(Collections.emptyList());
        }

        // 查询 Redis，按照距离排序、分页
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> content = search.getContent();
        if(from >= content.size()){
            return Result.ok(Collections.emptyList());
        }

        List<Long> ids = new ArrayList<>(content.size());
        Map<String, Distance> distanceMap = new HashMap<>(content.size());
        // 截取 from ~ end 的部分
        content.stream().skip(from).forEach(result -> {
            // 获取店铺 id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        String join = StrUtil.join(",", ids);
        // 根据 id 查询 shop
        List<Shop> shopList = query().in("id", ids).last("order by field(" + join + ")").list();

        for (Shop shop : shopList) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }

        return Result.ok(shopList);
    }

}
